1. Field of the Invention
This invention relates to a cable for spot welding for use in the automobile industry, in the manufacture of railway cars, in ship-building and in production lines for electrical parts and for other applications. More specifically, the invention relates to a terminal which is adapted to fix the end of an air-cooled cable composed of core wires and to connect the end of the cable to another electrical circuit.
2. Description of the Prior Art
In a spot welding operation, the cable of a welding gun experiences repetitive physical fatigue from bending and twisting since the welding gun is manipulated through a wide variety of angles to perform welding at the prescribed locations. In addition, the cable is repeatedly raised in temperature since a high welding current of from 8000 to 15,000 amperes repeatedly flows through the cable. At such times the core wires of the cable strike one another forcefully owing to the generation of an impact force referred to as "kick". Although the exterior of the cable is generally covered with a hose for protection and insulation purposes, this cannot mitigate the physical fatigue and electrical impact force described above. The physical fatigue and electrical impact are concentrated at the portion where the cable is connected to a fixed terminal, and both physical and electrical impact forces repeatedly act upon the cable whenever the spot welding operation is carried out. This leads to cable severence at the connected portion. Furthermore, whenever a large current flows, the cable temperature is elevated and wires may break as a result of overheating. Such a damaged cable would no longer be capable of withstanding use and would naturally require replacement. However, this results in higher cable costs, increased downtime necessary for cable replacement, and higher costs necessary for the labor involved in cable replacement. It is extremely uneconomical when a considerably long period of time is required for cable replacement at a production line where workpieces are being welded at a high production speed of one workpiece per tens of seconds.